[inferbo] Fix the model of Collections.emptySet

Summary: Models of Java's Collection mistakenly assumed that there was an argument for empty set whereas `Collections.emptySet()` doesn't have any actuals. This diff fixes that an also removes the type argument from the corresponding model definition.

Reviewed By: skcho

Differential Revision: D16582314

fbshipit-source-id: d4304dc60

infer/src/bufferoverrun/bufferOverrunModels.ml

@@ -680,7 +680,7 @@ module Collection = struct
     {exec; check= no_check}
 
 
-  let new_collection _ =
+  let new_collection =
     let exec = create_collection ~length:Itv.zero in
     {exec; check= no_check}
 
@@ -710,9 +710,9 @@ module Collection = struct
 
   let add coll_id = {exec= change_size_by ~size_f:Itv.incr coll_id; check= no_check}
 
-  let singleton_collection el_var =
+  let singleton_collection =
     let exec env ~ret:((id, _) as ret) mem =
-      let {exec= new_exec; check= _} = new_collection el_var in
+      let {exec= new_exec; check= _} = new_collection in
       let mem = new_exec env ~ret mem in
       change_size_by ~size_f:Itv.incr id ~ret env mem
     in
@@ -862,17 +862,17 @@ module Call = struct
       ; -"malloc" <>$ capt_exp $+...$--> malloc ~can_be_zero:false
       ; -"calloc" <>$ capt_exp $+ capt_exp $!--> calloc ~can_be_zero:false
       ; -"__new"
-        <>$ capt_exp_of_typ (+PatternMatch.implements_pseudo_collection)
+        <>$ any_arg_of_typ (+PatternMatch.implements_pseudo_collection)
         $+...$--> Collection.new_collection
       ; -"__new"
-        <>$ capt_exp_of_typ (+PatternMatch.implements_collection)
+        <>$ any_arg_of_typ (+PatternMatch.implements_collection)
         $+...$--> Collection.new_collection
       ; -"__new"
-        <>$ capt_exp_of_typ (+PatternMatch.implements_map)
+        <>$ any_arg_of_typ (+PatternMatch.implements_map)
         $+...$--> Collection.new_collection
       ; +PatternMatch.implements_map &:: "size" <>$ capt_exp $!--> Collection.size
       ; -"__new"
-        <>$ capt_exp_of_typ (+PatternMatch.implements_org_json "JSONArray")
+        <>$ any_arg_of_typ (+PatternMatch.implements_org_json "JSONArray")
         $+...$--> Collection.new_collection
       ; -"__new" <>$ capt_exp $+...$--> malloc ~can_be_zero:true
       ; -"__new_array" <>$ capt_exp $+...$--> malloc ~can_be_zero:true
@@ -961,15 +961,13 @@ module Call = struct
         (* model sets as lists *)
       ; +PatternMatch.implements_collections
         &::+ unmodifiable <>$ capt_exp $--> Collection.iterator
-      ; +PatternMatch.implements_collections
+      ; +PatternMatch.implements_collections &:: "singleton" <>--> Collection.singleton_collection
-        &:: "singleton" <>$ capt_exp $--> Collection.singleton_collection
+      ; +PatternMatch.implements_collections &:: "emptySet" <>--> Collection.new_collection
-      ; +PatternMatch.implements_collections
-        &:: "emptySet" <>$ capt_exp $--> Collection.new_collection
         (* model maps as lists *)
       ; +PatternMatch.implements_collections
-        &:: "singletonMap" <>$ capt_exp $--> Collection.singleton_collection
+        &:: "singletonMap" <>--> Collection.singleton_collection
       ; +PatternMatch.implements_collections
-        &:: "singletonList" <>$ capt_exp $--> Collection.singleton_collection
+        &:: "singletonList" <>--> Collection.singleton_collection
       ; +PatternMatch.implements_collection
         &:: "get" <>$ capt_var_exn $+ capt_exp $--> Collection.get_or_set_at_index
       ; +PatternMatch.implements_collection

infer/tests/codetoanalyze/java/performance/CollectionsTest.java

@@ -60,4 +60,9 @@ class CollectionsTest {
   void unmodifiable_set(Set<Integer> set) {
     for (Integer el : Collections.unmodifiableSet(set)) {}
   }
+
+  void emptySet_zero() {
+    Set<String> set = Collections.emptySet();
+    for (String s : set) {}
+  }
 }

infer/tests/codetoanalyze/java/performance/issues.exp

@@ -67,6 +67,9 @@ codetoanalyze/java/performance/CollectionTest.java, CollectionTest.nested_iterat
 codetoanalyze/java/performance/CollectionTest.java, CollectionTest.sparse_array_linear(android.util.SparseArray):void, 1, EXPENSIVE_EXECUTION_TIME, no_bucket, ERROR, [with estimated cost 2 + 5 ⋅ arr.length + 3 ⋅ (arr.length + 1), degree = 1,{arr.length + 1},Loop at line 64,{arr.length},Loop at line 64]
 codetoanalyze/java/performance/CollectionsTest.java, CollectionsTest.binary_search_log(java.util.List):int, 1, EXPENSIVE_EXECUTION_TIME, no_bucket, ERROR, [with estimated cost 2 + log(list.length), degree = 0 + 1⋅log,{list.length},Modeled call to Collections.binarySearch]
 codetoanalyze/java/performance/CollectionsTest.java, CollectionsTest.copy_linear(java.util.List,java.util.List):void, 1, EXPENSIVE_EXECUTION_TIME, no_bucket, ERROR, [with estimated cost 3 + list_to.length, degree = 1,{list_to.length},Modeled call to Collections.copy]
+codetoanalyze/java/performance/CollectionsTest.java, CollectionsTest.emptySet_zero():void, 0, ZERO_EXECUTION_TIME, no_bucket, ERROR, []
+codetoanalyze/java/performance/CollectionsTest.java, CollectionsTest.emptySet_zero():void, 2, CONDITION_ALWAYS_FALSE, no_bucket, WARNING, [Here]
+codetoanalyze/java/performance/CollectionsTest.java, CollectionsTest.emptySet_zero():void, 2, CONDITION_ALWAYS_TRUE, no_bucket, WARNING, [Here]
 codetoanalyze/java/performance/CollectionsTest.java, CollectionsTest.fill_linear(java.util.List,java.lang.String):void, 1, EXPENSIVE_EXECUTION_TIME, no_bucket, ERROR, [with estimated cost 3 + list.length, degree = 1,{list.length},Modeled call to Collections.fill]
 codetoanalyze/java/performance/CollectionsTest.java, CollectionsTest.reverse_linear(java.util.List):void, 1, EXPENSIVE_EXECUTION_TIME, no_bucket, ERROR, [with estimated cost 2 + list.length, degree = 1,{list.length},Modeled call to Collections.reverse]
 codetoanalyze/java/performance/CollectionsTest.java, CollectionsTest.shuffle_linear(java.util.List,java.util.Random):void, 1, EXPENSIVE_EXECUTION_TIME, no_bucket, ERROR, [with estimated cost 3 + list.length, degree = 1,{list.length},Modeled call to Collections.shuffle]